Drilling of wells for exploration or production of petroleum fluids like oil, condensate and gas is very expensive, particularly offshore where the day rate of a drilling unit can exceed 500 000 USD.
In the process of drilling, mud is essential in order to control the pressure of the well, provide lubrication and cooling, and for transport of drilled out material, often called cuttings. Different muds are needed for different conditions, depending on several factors, resulting in mud of specific properties for specific conditions. The best known parameters characterizing mud are viscosity and density. The mud can be based on water, or mineral or hydrocarbon oil and can include traditional materials like bentonite clays or other natural materials or synthetic materials. The selection and formulation of the mud is managed by the mud engineer.
It is industry practice to monitor the properties of the mud returning from the well. This is essential in order to detect traces of hydrocarbons, particularly traces of gas, which can give an early warning of a gas kick (uncontrolled pressure rise).
However, with respect to the mud to be pumped down into the well by the mud pumps, it is industry practice to take manual samples in order to ensure that the mud properties are as intended. The sample must typically be sent to a laboratory, either on the drilling rig or on land at a remote location, and the process of analyzing may take considerable time. For drilling operations offshore, time is very expensive, and even a moderate reduction in wasted time can have a significant impact on the economy of the operation. Another aspect is the increased safety if it could be ensured at all times that only mud having the correct properties is pumped down the drill string.
Many technologies exist for data acquisition and processing of data. Many technologies exists for collecting samples of mud coming up from the well, and some for collecting samples of mud as mixed and to be pumped down the drill string. In addition, many technologies exist for analyzing single parameters of the mud.
Some related technology is described in the patent publications CN 201802388, GB 2445209, CA 2005195, MX 2011006044 and U.S. Pat. No. 6,378,628.
However, a demand still exists for technology in order to: reduce the time spent for monitoring the mud properties; provide a continuous monitoring; provide data for more parameters than current industry standard practice: reduce the risk of pumping incorrect mud composition; reduce waste, tankage requirement and ineffective drilling unit time and increase safety. The objective of the present invention is to meet the demand.